text: Transesterification, which involves changing one ester into another one, is widely practiced:
  Like the hydrolysation, transesterification is catalysed by acids and bases. The reaction is widely used for degrading triglycerides, e.g. in the production of fatty acid esters and alcohols. Poly(ethylene terephthalate) is produced by the transesterification of dimethyl terephthalate and ethylene glycol: 
  A subset of transesterification is the alcoholysis of diketene. This reaction affords 2-ketoesters.